Chemical-and X-ray-induced antitumor cell-mediated immunity to rat fetal cells

Gastrointestinal cancer was induced in Fischer F344 inbred rats in their: (i) small bowel by localized exposure to X-rays, (ii) colon by administration of the carcinogen 1,2-dimethylhydrazine (DMH), and (iii) pancreas by implantation of the polyaromatic hydrocarbon 7,12-dimethylbenz[a]anthracene into the 'head' of the organ. A common tumor-associated fetal antigen (TAFA) and cell-mediated immunity (CMI) was noted in these three animal cancer models. The present investigation was a preliminary attempt to delineate the relationship between the TAFA and CMI. Findings indicate that those cells having the TAFA are suitable targets for cytotoxicity expressed by the educated peripheral blood lymphoid cells (PBLC) obtained from the tumor-bearing rats, and that components containing the TAFA (tumor cell membrane extracts, serum) are capable of competing with such targets in the CMI responses. In addition, cells derived from 16-18-day-old rat fetuses were found to be significantly injured and killed by these PBLC. Probably the most important results in this initial study was the findings that cancers induced by these three completely different cellular mechanisms in different tissues resulted in common TAFA and CMI responses and that there is a relationship between these two phenomena which is at this time unclear.